Remove libnativehelper/include/nativehelper from include_dirs

Needed as libnativehelper is part of the runtime module and so will not
be present in an unbundled build, instead its build targets will be
provided as prebuilts.

Bug: 134379140
Test: m checkbuild
Change-Id: If1c680dd70a6662623697ba32a257b372bbeaf30